Liquid crystal display devices are being used in watches, calculators, various measurement instruments, automobile panels, word processors, electronic organizers, printers, computers, televisions, clocks, advertising boards, etc. Typical examples of the liquid crystal display mode include TN (twisted nematic) mode, STN (super twisted nematic) mode, and vertical alignment or IPS (in-plane switching) that uses TFT (thin film transistors) mode. Liquid crystal compositions that are used in these liquid crystal display devices are required to be stable against external stimuli such as moisture, air, heat, and light, stay in a liquid crystal phase in a temperature range as wide as possible about room temperature, exhibit low viscosity, and operate at a low drive voltage. A liquid crystal composition is constituted by several to dozens of compounds in order to optimize dielectric anisotropy (Δ∈), refractive index anisotropy (Δn), and other properties for individual display devices.
In a horizontal alignment-type display such as a TN, STN, or IPS (in-plane switching) display, a liquid crystal composition having a positive Δ∈ is used. There is a report of a drive mode in which the liquid crystal composition having a positive Δ∈ is made to align vertically in the absence of applied voltage and a horizontal electric field is applied to perform display. There is an increasing need for a liquid crystal composition with a positive Δ∈.
Low voltage driving, high speed response, and a wide operation temperature range are highly desirable in these driving modes. In other words, a positive Δ∈ with a large absolute value, low viscosity (η), and a high nematic phase-isotropic liquid phase transition temperature (Tni) are desirable. Due to setting of Δn×d, which is the product of Δn and a cell gap (d), the Δn of the liquid crystal composition needs to be adjusted to be within an appropriate range in accordance with the cell gap. Since high-speed response is important in order to use a liquid crystal display device in a television or the like, a liquid crystal composition having a low rotational viscosity (γ1) is required.
Examples of the structure of a liquid crystal composition disclosed so far include liquid crystal compositions containing compounds represented by formulae (A-1a) and (A-1b) below and compounds represented by formulae (B-1a) to (B-1c) below (refer to PTL 1):
and liquid crystal compositions containing a compound represented by formula (A-3) below, compounds represented by formulae (A-2a) and (A-2b) below, and a compound represented by formula (B-2a) below (refer to PTL 2):

These liquid crystal compositions are characterized in that there are three ring structures in a liquid crystal compound having a positive Δ∈ and that —CF2O— structure is included as a linking group.
As the usage of liquid crystal display devices expands, the operation methods and the production methods therefor have undergone significant changes. In order to meet the changes, optimization of the properties other than basic physical property values considered in the related art has become necessary. In other words, VA mode and IPS mode liquid crystal display devices that use liquid crystal compositions have become prevalent and display devices with super large screen size of 50 or larger have been put to practice and are now being widely used. As the substrate size increases, a one drop fill (ODF) method has become the mainstream method for injecting a liquid crystal composition into a substrate, thereby replacing a conventional vacuum injection method. However, degradation of display quality caused by drop marks that occur when the liquid crystal composition is dropped onto a substrate has become a problem.
In a liquid crystal display device production process based on the ODF method, optimum amounts of liquid crystals need to be injected by dropping according to the size of a liquid crystal display device. If the injection amount significantly deviates from the optimum value, the balance among the pre-designed refractive index and drive electric field will be adversely affected and display defects such as nonuniformity and poor contrast will result.
In particular, for a small-size liquid crystal display device frequently used in smart phones that have become prevalent in recent years, it is difficult to control the deviation from the optimum value within a particular range since the optimum amount of the liquid crystals to be injected is small.
Accordingly, in order to produce liquid crystal display devices while maintaining high yield, for example, the influence of rapid pressure changes inside the dropping machine or impacts that occur during dropping of liquid crystals needs to be reduced and properties that enable stable dropping of liquid crystals for a long time are required.
As such, a liquid crystal composition used in an active matrix-drive liquid crystal display device driven by TFTs and the like is required to maintain properties and performance, such as high-speed response, desirable for a liquid crystal display device, exhibit high resistivity and high voltage holding ratio and be stable against external stimuli such as light and heat as have been emphasized in the past, and to be developed by taking into account the liquid crystal display device production method.